Essiac/Flor Essence (PDQ®)
• Essiac and Flor Essence are herbal tea mixtures that are sold worldwide as health tonics or herbal dietary supplements (see Question 1).
• Essiac was first promoted as a cancer treatment in the 1920s. Flor Essence was created a number of years later (see Question 2).
• Supporters of Essiac and Flor Essence say that these products make the immune system stronger, have anti-inflammatory effects, relieve pain, decrease side effects, and show anticancer activity (see Question 3).
• Laboratory, animal, and clinical (human) studies with Essiac and Flor Essence have not reported clear evidence of an anticancer effect (see Question 5 and Question 6).
• The U.S. Food and Drug Administration has not approved Essiac or Flor Essence as a cancer treatment (see Question 8).

Questions and Answers About Essiac and Flor Essence
1. What are Essiac and Flor Essence?
Essiac and Flor Essence are herbal tea mixtures that have been used as anticancer treatments. They have been used to treat other health conditions also, including diabetes, AIDS, and gastrointestinal diseases.
Essiac is reported to contain 4 herbs:
o Burdock root.
o Indian rhubarb root.
o Sheep sorrel.
o Slippery elm (the inner bark).
Flor Essence is reported to contain the same 4 herbs found in Essiac plus these 4 other herbs:
o Watercress.
o Blessed thistle.
o Red clover.
o Kelp.
Different batches of these mixtures may contain different ingredients or amounts and the effects may not always be the same.
Essiac and Flor Essence are sold worldwide as health tonics or herbal dietary supplements. One company sells Flor Essence and several companies make and sell mixtures called Essiac. This summary refers to the trademarked (brand name) mixtures only.
2. What is the history of the discovery and use of Essiac and Flor Essence as complementary or alternative treatments for cancer?
A nurse in Canada first began to promote Essiac as a cancer treatment in the 1920s. Today, Essiac and Flor Essence may be sold as herbal supplements as long as they do not claim to treat or cure cancer.
o In 1922, a breast cancer patient gave the Essiac formula to the nurse and said it had cured her disease. The patient said the formula came from an Ontario Ojibwa Native American medicine man.
o In 1934, the nurse opened a cancer clinic in Ontario and gave Essiac to patients free of charge. In 1938, the Royal Cancer Commission of Canada visited the clinic but found little evidence that Essiac was effective. The nurse closed the clinic in 1942 but continued to give Essiac to patients until the late 1970s.
o Between 1959 and the late 1970s, the nurse worked with an American doctor to study Essiac in the laboratory and in people and to promote its use. They also created the formula now called Flor Essence. The results of their studies were not reported in any peer-reviewed scientific journals. Most scientific journals have experts who review research reports before they are published, to make sure that the evidence and conclusions are sound. This is called peer review. Studies published in peer-reviewed scientific journals are considered to be better evidence.
o In 1977, the nurse gave the formula for Essiac to a company in Canada. In 1978, the government of Canada allowed this company to do clinical studies (research studies with people) on the safety and effectiveness of Essiac. In 1982, it withdrew its permission (see Question 6). This company tried to have Essiac approved as a drug by the US Food and Drug Administration (FDA), but did not get approval.
o In the 1980s, companies making Essiac-like products began to sell the mixtures as health tonics. Because these companies did not make claims that it would treat or cure certain diseases, Essiac did not come under laws that regulate it as a drug.
3. What is the theory behind the claim that Essiac and Flor Essence are useful in treating cancer?
Supporters of Essiac and Flor Essence say that when the herbs they contain are mixed in exact amounts, the mixtures make the immune system stronger, have anti-inflammatory effects (decrease swelling, redness, and pain), and show anticancer activity. Individual herbs in the Essiac and Flor Essence formulas have been shown to have these effects, but some of these herbs also have been shown to help cancer grow. Some supporters of Essiac recommend that conventional therapy (such as chemotherapy and radiation therapy) not be used at the same time as Essiac because that may prevent Essiac from being effective.
There is no evidence reported in peer-reviewed scientific journals to show that the exact formulas of Essiac and Flor Essence are effective in patients with cancer or other health conditions, or that conventional therapies interfere with the effects of Essiac. See the PDQ health professional summary on Essiac/Flor Essence for more information on theory.
4. How are Essiac and Flor Essence administered?
Essiac and Flor Essence are taken orally (by mouth) as herbal teas. According to the companies that make the teas, the proper dose of Essiac depends on why a person is taking it. The maker recommends that Essiac be taken for 12 weeks in a row. The maker of Flor Essence states that adults may take between 30 and 360 milliliters (1 to 12 fluid ounces) of Flor Essence tea a day, depending on individual needs, and may take it on an ongoing basis.
The makers of Essiac and Flor Essence state that the products can be used with other therapies. Some supporters of Essiac, however, recommend that patients avoid any other anticancer therapy (such as chemotherapy or radiation therapy) when taking Essiac, because it may interfere with immune system function and prevent Essiac from working effectively.
5. Have any preclinical (laboratory or animal) studies been conducted using Essiac or Flor Essence?
Research in a laboratory or using animals is done to find out if a drug, procedure, or treatment is likely to be useful in humans. Animal tumor models are used to learn how a cancer may progress and to test new treatments. These preclinical studies are done before any testing in humans is begun. The following laboratory and animal studies of Essiac have been reported:
o In the mid 1970s, the Memorial Sloan-Kettering Cancer Center (MSKCC) in New York City tested dried and liquid samples of Essiac in 8 experiments involving the S–180 mouse sarcoma tumor model (a type of animal model used to study treatment). Researchers found that Essiac did not make the immune system more active and did not act as an anticancer drug.
o In the early 1980s, researchers at MSKCC tested Essiac again. They found no anticancer activity after doing 17 studies that used a variety of animal leukemia models and other tumor models.
o In 1983, the National Cancer Institute (NCI) tested a liquid sample of Essiac in the mouse P388 lymphocytic leukemia tumor system but found no anticancer activity. Very high doses of Essiac killed the test animals. Scientists, however, do not know how this finding applies to people who take more than the maker’s recommended doses of Essiac.
o In 2004, a laboratory study at Indiana University-Purdue University reported that Essiac slowed the growth of prostate cancer cells.
Studies of Flor Essence have shown differing results:
o Two laboratory studies reported that Flor Essence made tumor cells grow.
o Another laboratory study reported that high doses of both Flor Essence and Essiac herbal teas reduced the growth of cancer cells.
o A 2004 animal study of Flor Essence found that it increased breast tumor growth in rats.
Laboratory and animal studies have reported on the effects of some of the chemicals found in the different herbs used to make Essiac and Flor Essence. These studies report that certain chemicals may:
o Prevent cell damage that can lead to cancer.
o Reduce swelling, redness, and pain.
o Have an effect on the body similar to the hormone estrogen.
o Kill cancer cells.
It is not known if taking Essiac and Flor Essence products can give humans enough of the chemicals that produce these effects.
6. Have any clinical trials (research studies with people) of Essiac or Flor Essence been conducted?
No results of clinical studies (research studies with people) of Flor Essence have been reported. In addition, no reports of clinical trials of Essiac have been reported in peer-reviewed scientific journals. Brief descriptions of one incomplete clinical trial and one review of reports on cancer patients who took Essiac have been published, however.
o In 1978, the Canadian government gave permission to a Canadian company to begin studying Essiac for safety and effectiveness. In 1982, the government withdrew its permission after it found that the company was not keeping all batches of Essiac exactly the same and was not following the proper rules for clinical trials. A review of data from this incomplete study showed no clear evidence of improved survival in cancer patients who took Essiac. Findings also showed that Essiac was not toxic (harmful).
o In the early 1980s, the Canadian government reviewed information on 86 cancer patients who had taken Essiac. This was a review of case summaries written by the doctors; the original patient records were not reviewed. The researchers reported that it was not clear if changes in the patients’ conditions were caused by Essiac or something else.
7. Have any side effects or risks been reported from Essiac or Flor Essence?
The only reported side effects caused by Essiac are nausea and vomiting. According to the company making Flor Essence, side effects may include increased bowel movements, frequent urination, swollen glands, skin blemishes, flu-like symptoms, and slight headaches.
8. Is Essiac or Flor Essence approved by the FDA for use as a cancer treatment in the United States?
The U.S. Food and Drug Administration (FDA) has not approved Essiac or Flor Essence to treat cancer or any other medical condition.
Companies sell Essiac and Flor Essence as health tonics or herbal dietary supplements, which the FDA regulates as foods, not drugs. Essiac or Flor Essence would have to be approved by the FDA as a drug for companies to claim that the products treat or prevent a disease.